(1) Technical
The present invention relates to a line concentration system, which is in particularly useful in a small size exchange system, e.g., a private branch exchange system.
(2) Description of the Related Art
In a rather large size exchange system, e.g., in an exchange station in a public telephone network, line concentrators are provided between line circuits and speech path exchange circuits for handling a greater number of channels in a subscriber side in an exchange circuit side. Concentration rates for concentrators are respectively selected according to traffic intensities in the subscriber side capacities in the exchange circuit side. Generally, less traffic in the subscriber side requires a greater concentration rate in a concentrator to effectively utilize the total capacity of the exchange system.
However, in conventional concentrators, a concentration rate in a concentrator cannot be easily changed, i.e., the concentration rate is fixed. Further, in a rather small size exchange system, e.g., a private branch exchange system, no concentrator is provided, i.e., the concentration rate is one.
Namely, in the conventional exchange system, to change a concentration rate, a plurality of concentrators for respective concentration rates must be provided. Therefore, ineffective spaces for installing a plurality of concentrators are necessary in the conventional exchange system, and a troublesome operation is necessary to disconnect a group of subscriber channels from one concentrator and connect the group to another concentrator to change the concentration rate.